This invention concerns apparatus for pre-conditioning primary and auxiliary television signal information during an encoding process so that the auxiliary information can be efficiently and accurately recovered from the primary information during a subsequent decoding process.
A conventional television receiver, such as a receiver in accordance with NTSC broadcast standards adopted in the United States and elsewhere, has a 4:3 aspect ratio (the ratio of the width to the height of a displayed image). Recently, there has been interest in using higher aspect ratios for television receiver systems, such as 2:1, 16:9 or 5:3, since such higher aspect ratios more nearly approximate or equal the aspect ratio of the human eye than does the 4:3 aspect ratio of a conventional television receiver. Video information signals with a 5:3 aspect ratio have received particular attention since this ratio approximates that of motion picture film, and thus such signals can be transmitted and received without cropping the image information. However, widescreen television systems which simply transmit signals having an increased aspect ratio as compared to conventional systems are incompatible with conventional aspect ratio receivers. This makes widespread adoption of widescreen systems difficult.
It is therefore desirable to have a widescreen system which is compatible with conventional television receivers. One such system is disclosed in a copending U.S. patent application of C. H. Strolle et al., Ser. No. 078,150 titled "Compatible Widescreen Television System", filed July 27, 1987. It is even more desirable to have such a compatible widescreen system with provisions for enhancing or extending the definition of the displayed image so as to provide extra image detail. For example, such widescreen EDTV (extended definition television) system may include apparatus for providing a progressively scanned image.
In a compatible widescreen system, it may be necessary to transmit auxiliary video information together with existing standard information in encoded form. It is herein recognized as desirable to pre-condition such auxiliary information at an encoder so as to facilitate the efficient and accurate recovery of such auxiliary information at a decoder.